Multiple subcarrier signals are adopted in the multicarrier modulation technique, in which data streams are divided into several sub-data streams, so that the sub-data streams have much lower transmission bit rates, and these data are used to modulate several subcarriers, respectively. Multicarrier modulation signals are characterized in having relatively low transmission rates of subcarrier data and relatively long periods of code elements. Multicarrier modulation may be realized in multiple technical ways, such as discrete multi-tone (DMT), and orthogonal frequency division multiplexing (OFDM), etc.
A problem existed in the multicarrier modulation signals is that their peak to average power ratios (PAPRs) are relatively high. In practical applications, a peak value of an output signal of a transmitter is often limited, hence, in order to increase average power of the signals, the PAPRs of the signals need to be lowered. One of the most often used methods is to perform clipping directly on the multicarrier modulation signals. The multicarrier modulation signals are formed by superimposing multiple subcarrier signals, hence, in some special bitmaps, extremely high PAPRs will occur. Clipping operations on these symbols of extremely high PAPRs will produce very large clipping distortion, thereby resulting in burst errors in these symbols. Although a probability of occurrence of such burst errors is not high and its effect on an average bit error rate is relatively few, the burst errors will result in a failure of forward error correction (FEC) decoding, thereby causing a communication failure. Therefore, the clipping distortion needs to be estimated and the multicarrier signals need to be compensated according to a result of estimation.
Currently, an existing method is to reestablish time-domain signals and repeat processes of clipping at a receiving end after judging received multicarrier frequency-domain signals, and compensate for the clipping distortion, so as to eliminate the effect of the clipping distortion on the communication system. FIG. 1 is a flowchart of an existing method for compensating clipping distorting of multicarrier signals. As shown in FIG. 1, at a transmitting end, coding, interpolation and mapping, inverse fast Fourier transform (IFFT), clipping, fast Fourier transform (FFT), out-of-band removal and inverse fast Fourier transform (IFFT) are performed on signal data, which are transmitted by a transmission antenna; where, the inverse fast Fourier transform, clipping, fast Fourier transform and out-of-band removal constitute clipping and filtering processing; and at a receiving end, de-mapping and sorting, decoding, interpolation and mapping are performed on received signals after fast Fourier transform is performed on them, and the clipping and filtering processing performed at the transmitting end. i.e. the inverse fast Fourier transform, clipping, fast Fourier transform and out-of-band removal, are repeated on the signals after being performed interpolation and mapping, then a clipping noise component {circumflex over (D)} of each subcarrier is estimated according to the signals after being performed the interpolation, mapping and attenuation, a channel gain H of each subcarrier is estimated according to the clipping noise component, and the received signals are compensated according to the channel gain H.
It should be noted that the above description of the background art is merely provided for clear and complete explanation of the present disclosure and for easy understanding by those skilled in the art. And it should not be understood that the above technical solution is known to those skilled in the art as it is described in the background of the present disclosure.